/Engine/Plugins/Animation/DeformerGraph/Source/OptimusCore/Public/OptimusNode.h
Add a new grouping pin. This is a pin that takes no connections but is shown as collapsible in the node UI.
[UOptimusNodePin](API\Plugins\OptimusCore\UOptimusNodePin) * AddGroupingPin ( [FName](API\Runtime\Core\UObject\FName) InName, [EOptimusNodePinDirection](API\Plugins\OptimusCore\EOptimusNodePinDirection) InDirection, [UOptimusNodePin](API\Plugins\OptimusCore\UOptimusNodePin) * InBeforePin )